1. Field of the Invention
The present invention relates to an automatic transmission locking mechanism for an automatic transmission for a vehicle and more particularly to an automatic transmission locking mechanism for an automatic transmission of a reduced axial dimension for a vehicle.
2. Description of the Prior Art
In most front-engine front-drive automobiles (designated as "FF automobiles" hereinafter), the engine is mounted transversely. Accordingly, the axial dimension of an automatic transmission for an FF automobile is required to be reduced, particularly when the engine is mounted transversely.
Most conventional automatic transmission locking mechanisms interlocked with a manual shift lever employ the following constitution. That is, a lever is joined integrally to a manual shaft which is turned through the manual operation of a manual shift lever, the rear end of a cam rod provided intermediately with a cam is linked to the lever and the free end of a pawl with a detent is pushed up and thereby the pawl is turned about the axis of turning thereof when the cam is caused to run on a slope formed in a bracket supporting the front portion of the cam rod extending formed from the cam, whereby the detent engages with a parking gear fixed to the output shaft of the transmission to lock the output shaft. A spring mechanism is included in the automatic transmission locking mechanism to retain the pawl with the detent at the released position while the vehicle is running in order to prevent the accidental contact between the detent and the parking gear during running. According to the prior art, such a spring mechanism has been constituted in a form in which the pawl with the detent is retained by the resilience of a torsion spring mounted round a shaft on which the pawl is turned and engaged at one end thereof with the pawl and at the other end thereof with a case. However, such a conventional spring mechanism required a shaft of an increased length for the pole to mount a torsion spring and hence an increased axial dimension of the mechanism and a strong spring. Furthermore, provision of the torsion spring on the shaft on which the pawl is turned (designated as "the pole shaft" hereinafter) requires difficult work in fitting the pawl on or in removing the pole from the pawl shaft.